Debates are always a big part of any U.S. presidential campaign, but with Hillary Clinton and Donald Trump both having unusually low favorability ratings, this year's debates could be more influential than usual.

"Because the electorate is so volatile this year, it doesn't take nearly as much to get a loosely aligned voter to switch his allegiance," Dan Schnur, director of the University of Southern California's political institute, told The Associated Press.

In a Washington Post-ABC News poll released this week, 41 percent of Americans have a favorable impression of Clinton, while 56 percent have an unfavorable one.

It is the lowest rating Clinton has had in her quarter-century in national public life, the Post reported.

Trump fares worse in the new poll. Thirty-five percent of Americans have a favorable impression of him, compared with 63 percent unfavorable, the Post reported.

4 debates before November vote

The first of three presidential debates will be held September 26 at Hofstra University in Hempstead, New York. NBC News anchor Lester Holt will moderate the event.

The second debate will be held October 9 at Washington University in St. Louis, Missouri. The event — to be co-moderated by CNN anchor Anderson Cooper and ABC global affairs correspondent Martha Raddatz — will be a town hall-style meeting, with questions coming from audience members and from people following the debate via social media.

The third debate, with Fox News anchor Chris Wallace as moderator, will be held October 19 at the University of Nevada in Las Vegas.

CBS journalist Elaine Quijano will moderate the lone vice presidential debate between Democrat Tim Kaine and Republican Mike Pence. It will be held October 4 at Longwood University in Farmville, Virginia.

Trump wants to 'negotiate'

Steve Scully of the cable news network C-SPAN will be a backup moderator for all four debates, according to the Commission on Presidential Debates, a nonpartisan group that organizes the events.

Clinton has said she will take part in all three debates.

Trump also has agreed to participate, but says he wants to negotiate the debate conditions. His campaign did not immediately respond to a request for comment Friday.

With Trump in the mix, there's also plenty of potential for shock value.

Maybe a smackdown?

"Mass audiences are going to be tuning in to look for a smackdown," Eric Dezenhall, a Washington crisis management consultant, told the AP.

FILE - Democratic presidential candidates, former Secretary of State Hillary Clinton, left, and Sen. Bernie Sanders, I-Vt. talk over each other during the Democratic presidential primary debate in Charleston, South Carolina, Jan. 17, 2016.

In the primaries, Trump grabbed the spotlight in the opening minutes of the first of a dozen GOP debates, when he was the only candidate to refuse to rule out a third-party run for president. The Republican primary debates were often raucous affairs, with name-calling and candidates talking over each other. Moderators often had trouble keeping the debate on track.

The nine Democratic debates showcased Clinton as an experienced debater, although the highlight may have been Bernie Sanders' curt dismissal of all the attention being paid to Clinton's "damn emails."

Knockout unlikely

Over the past half-century, general election debates have offered plenty of moments of televised high drama, but knockouts are rare.

In 1980, Ronald Reagan shone in his debate against then-President Jimmy Carter, scolding him with a gentle "there you go again," and posing a pointed closing question: "Are you better off than you were four years ago?" Pollsters reported a resulting sharp shift in public opinion, said Alan Schroeder, author of Presidential Debates: Forty Years of High-Risk TV.

Two decades earlier, in the first televised debates, Richard Nixon, appearing sickly and unprepared, never recovered from his disastrous performance in the first of three 1960 debates with then-Senator John F. Kennedy, who would win the presidency.

This year, given Trump's unpredictability, "You've got a recipe for a highly combustible situation," Schroeder said of the debates. "For viewers, it creates a scenario that virtually compels them to watch.

"Anything that happens on that stage will therefore be magnified exponentially," he added.